Actually you will want to be weary of smaller bore inserts as markers with A5 threading allow for the bolt to very slightly enter into the barrel. I have a .683 insert on my DW barrel and the bolt will sometimes catch and pull the insert back, so I hunted down a boomstick back in .686 and it has worked great! Just wanted to give you a heads up!

Looking for a good barrel for my crossover also..my buddy has an A5 thread stifi barrel, but the bolt catches it, so it is a no-go. Havent ordered the deadly null 14in(read that it is a good one for the crossover). want to see if there is another way to go

I just recently got a 12" Deadlywind Null and 6 piece iFit kit and love it a bunch. Even just using the Null barrel on its own works great. Attaching the kit to the barrel brings overall length to about 14".

Null is the only one of their barrels Deadly Winds recommends for the Crossover. The website say not to use the Fibur on the Crossover. GIJoe is right, the bolt will catch the smaller inserts.

its because freak inserts are not tapered, they are basically a tube that is the same size through out the entire length. The ifit kit has tapered inserts, so the end that is closest to the gun is larger then it narrows down to the selected bore size, this is why the ifit works better on the crossover then freak inserts. The bolt slides into the the tapered bigger end and doesn't stick like it does on the narrow end of the freak insert.